To fire a semi-automatic firearm, such as a pistol, the operator generally holds the grip of the firearm and squeezes the trigger, causing a round of ammunition that is situated in the barrel of the weapon to be struck be the hammer or firing pin. The strike from the hammer or firing pin causes the gun powder in the round to ignite, propelling the bullet from the cartridge of the round through and out of the barrel. In a semi-automatic firearm, additional bullets can be held in the magazine of the weapon. When a bullet is fired from the weapon, the recoil from firing ejects the spent cartridge, loads a new cartridge from the magazine, and resets the hammer and trigger on the weapon. Once the subsequent ammunition round is chambered into the barrel, the trigger can be squeezed again, causing another shot to be fired. Thus, for semi-automatic firearms, the time expended between shots is dependent on the operator's ability to physically squeeze the trigger. This is in contrast to an automatic weapon wherein the trigger is engaged once and the weapon automatically fires multiple ammunition rounds without the operator needing to squeeze the trigger a second or subsequent time.
Some government agencies regulate the purchase and use of both semi-automatic and automatic firearms, with automatic firearms generally being more regulated than semi-automatic firearms. Due to the heightened regulations for automatic firearms, semi-automatic firearm operators that desire to discharge rounds in rapid succession have turned to varied methods of doing so. One such method is call bump firing. Generally, bump firing uses forward force from the operator's non-trigger hand and the recoil of the firearm to push the trigger against the operator's trigger finger while keep the trigger finger stationary. The operator pushes the weapon forward while keeping pressure on the trigger, causing the weapon to fire rapidly. One crude method of bump firing is for the operator to place his or her finger from one hand on the trigger while gripping the weapon with the other hand and pushing the weapon against the trigger finger. Another technique employs the use of the operator's belt loop, wherein the operator's trigger finger is held in place by the belt loop while the operator's other hand is used to push the weapon forward. By maintaining pressure against the trigger finger while the weapon is firing, instead of squeezing the trigger after each shot, each round is fired in rapid succession. These bump firing techniques result in decreased accuracy, and because of the placement of the operator's trigger hand near the barrel of the weapon, increases the danger of accidental injury from hot gas and used chambers as they are discharged from the barrel. Also, these bump firing techniques require that the weapon be held with only one hand, increasing the chances that the operator will lose control of the weapon during operation.
To combat against these dangers and decreased accuracy, bump fire devices have been created for use on semi-automatic rifles, with the bump fire mechanism positioned in the butt of the rifle and frequently using force applied by the operator's shoulder to achieve the bump firing technique. However, such bump fire mechanisms cannot be applied to pistols, which do not have a butt, do not employ the operator's shoulder, and operate differently than pistols.